A United States Patent confers the right to "exclude others from making, using, offering to sell, selling, or importing the invention into the United States."  This right operates within the United States, and also extends to block importation into the United States of goods whose manufacture violated the patent.

In order to get a US Patent, there are several requirements which will be requested by the USPTO.  These requirements include the following:

1.  it must be Suitable Subject Matter

2.  it must have Utility

3.  it must be Novel, and

4.  it must be Non-Obvious

Suitable Subject Matter

According to US Patent Law an invention must fall within the following statutory subject matter:

1.  an article of manufacture

2.  a composition of matter

3.  a process or method

4.  new and useful improvements of the above

5.  any distinct and new variety of plant that is asexually reproduced

6.  any new, original, and ornamental design for an article of manufacture (design patent)

Utility

The requirement for utility basically requires that the invention do something.  Does it address or solve a problem?  This requirement is almost a formality because the threshold for tuility is very low.

Novelty

The requirement for novelty essentially requires that the invention is original.  This is a criterion which the USPTO places special emphasis upon.  For this reason, it is imperative to perform a prior art search for your invention.

Non-Obviousness

Perhaps the toughest and most contentious requirement.  This requirement seeks to limit patents to innovation which is not just trivial or so obvious.  It is often thought of as a supplement to the Novelty requirement.  In order to judge whither an ivnentionis obvious or not, the USPTO will use the standard of "one skilled in the art".  One skilled in the art is generally someone who has practiced in that field or industry for several years, has had formal training in that field or industry, etc.  Predictably, the process by which the USPTO determines the standard of "one skilled in the art" is fraught with confusion, debate and difficulty.